Sensor for monitoring concentration of gaseous substances

Abstract

The invention provides a sensor arrangement for monitoring the concentration of moisture and gaseous substances in ambient air. A gas sensitive intermediate layer is sandwiched between top and bottom electrodes, each of which comprises first and second interdigitated conductive elements, which are coupled to an opposite polarity voltage. The top and bottom electrodes are super-imposed on opposite sides of the gas-sensitive intermediate layer, with fingers of the top electrode having a voltage polarity which is opposite that of adjacent super-imposed fingers of the bottom electrode.

What is claimed is: 
     
       1. A sensor for determining concentration of gaseous substances, comprising: a gas sensitive intermediate layer sandwiched between top and bottom electrodes; wherein   each of said top and bottom electrodes comprises first and second interdigitated conductive fingers having respective first and second contacts which are connected to opposite polarity voltages;   said top and bottom electrodes are superimposed on opposite sides of said intermediate layer;   fingers of said top electrode are aligned in registration with fingers of said bottom electrode, forming registered pairs of oppositely disposed fingers; and   in each registered pair of fingers, a finger of said top electrode has a voltage polarity which is opposite that of an oppositely disposed finger of said bottom electrode.   
     
     
       2. Sensor according to claim 1 wherein said first and second contacts of said top electrode are superimposed adjacent said first and second contacts of said bottom electrode. 
     
     
       3. Sensor according to claim 1, further comprising a measuring resistance connected to said electrodes for measuring a voltage drop across said measuring resistance as an output of said sensor. 
     
     
       4. Sensor according to claim 1, wherein said sensor comprises a substrate made of Al 2  O 3 , and said electrodes are made from a material selected from the group consisting of platinum and gold.